Field
The present specification generally relates to optical fiber interconnects and, more specifically, to multi-core optical fiber interconnects with reduced optical signal time delays between core elements within the transmission interconnects.
Technical Background
In recent years optical fiber has become accepted as a viable alternative to traditional materials used for data signal communication. Optical fiber is now widely utilized in a variety of electronic devices to facilitate the high-speed communication of data signals at high bandwidths. However, as the speed and bandwidth of the electronic components in data communication devices increases, there is a corresponding need to increase the speed of optical interconnects which couple such devices. One solution to increase the speed of optical interconnects is to increase the fiber density of the optical interconnects and thereby realize high fiber count connectors. Another solution is to utilize multi-core optical fibers in which a plurality of core elements are disposed in a common cladding, thus reducing the overall bulk of the optical interconnect while increasing the fiber density (i.e., the core density).
One drawback of multi-core optical fibers is crosstalk between cores in the fiber. A requirement of low total crosstalk in interconnects limits the density of cores within the multi-core optical fiber, and thus the capacity scaling, compactness, and cost of the interconnect formed from the multi-core optical fiber. As such, crosstalk suppression has been a primary multi-core optical fiber research. To address crosstalk, trench-assisted homogeneous multi-core optical fibers have been proposed to achieve multi-core optical fibers with high core densities and reduced crosstalk. However, one issue of introducing a trench associated with each core is the significant increase in fiber manufacturing cost. To overcome this drawback, heterogeneous multi-core optical fibers have been proposed. In these multi-core optical fibers any two adjacent cores have slightly different effective refractive indexes which prevents phase-matching coupling between the cores, thereby suppressing crosstalk. However, the different propagating constants between the two cores produces large optical signal time delays between the cores, otherwise referred to as skew. This unwanted skew increases the difficulty of implementing crosstalk equalizers in a communication system. In addition, this unwanted skew prevents multi-core optical fibers from being used in communication systems which require minimized optical signal time delay between the cores, such as, parallel data transmission between multiple processors in data center applications.
Accordingly, a need exists for alternative interconnects utilizing multi-core optical fibers.